Soil Amendment Analysis for Riparian Revegetation

Location

Havasu National Wildlife Refuge
Needles, California

Client

Bureau of Reclamation, Lower Colorado Regional Office

Project Description

GSA restoration and soil scientists conducted a field study to determine if a soil amendment could improve irrigation distribution and enhance surface soil moisture retention in sandy soils. If effective, the amendment was anticipated to decrease the required irrigation volume, encourage native plant establishment, and enhance habitat quality for riparian birds.

A randomized complete block design was used to analyze three levels of amendment incorporation on two experimental fields. A subset of plots was instrumented with soil moisture sensors to monitor water content between irrigation events. The area was then hydroseeded with native riparian species.

Study results indicated an amendment rate of 25% or less by volume would decrease infiltration rates and therefore improve irrigation distribution. Soil moisture retention was likely increased by 25% amendment rates. Seedling establishment was limited due to salinity content of the amendment, which must be leached prior to planting for future applications.

Project Highlights